There are many industrial and environmental situations where water is isolated in a container, the water having volatiles contained therein. Commonly, air strippers are used to remove the volatiles from the water. The air stripper would include a pump for creating a vacuum over the water thereby causing the water to release the volatiles therefrom. Commonly, the air containing the volatiles is pumped from the tank into the atmosphere.
Recent environmental legislation prohibits much of the use of these air strippers in an uncontrolled fashion. To control the release of the volatiles into the atmosphere, carbon filters have been used to absorb the volatiles. These filters foul over time and must be replaced.
The inventor of the present invention has made several advances in the use of membrane technology for separating fluids, such as water and water soluble substances from relatively hydrophobic materials. For example, the U.S. Pat. No. 4,857,081 to Taylor, issued Aug. 15, 1989, discloses an apparatus and method for separating water from a water and hydrocarbon mixture and water from a water and halogenated hydrocarbon mixture. The device consists essentially of nonporous self-supported hollow fibers of regenerated cuproammonium cellulose. The membranes have the capacity of imbibing water from a stream of hydrocarbons or halogenated hydrocarbons contaminated with water. The water defuses to the other side of the membrane and is then removed from the other side of the membrane.
The inventors copending application Ser. No. 402,229 to Taylor, filed Sept. 5, 1989 discloses a composite membrane including a porous support membrane and a nonporous water and water soluble substance permeating membrane, such as the nonporous cuproammonium regenerated cellulose disposed over each of the pores for selectively permeating only water and water soluble substances through each of the pores.
Applicant herein provides a novel apparatus and method incorporating into the method a modified Soxhlet trap to provide a substantially passive, very low energy means of removing volatiles from water, retrieving the air used in the process as clean air back to the environment, and capturing the dense volatiles.
S. Franz Soxhlet (1848-1913) was a German food analyst. Soxhlet invented an apparatus including a flask and a condenser for the continuous extraction of alcohol-or ether-soluble materials. The apparatus is a closed system wherein a flask containing solvent and the soluble material is heated. The vapor generated therefrom travels through a 90 degree bend in a fluid conducting tube to a condensing chamber. The condensing chamber produces condensation of the solvent which travels through another fluid conducting conduit back to the flask while the vapor is released into the atmosphere.
Applicant has modified and combined a Soxhlet type trap with the inventor's novel membranes in order to provide a means for first removing from a water supply and then separating the air used therefor from the volatiles and trapping the volatiles.